1397 Umtata

1397 Umtata, provisional designation 1936 PG, is an asteroid from the background population of the asteroid belt's central region, approximately 21 kilometers in diameter. It was discovered by South-African astronomer Cyril Jackson at the Union Observatory in Johannesburg on 9 August 1936.[9] The asteroid was named after the South-African town of Mthatha, formerly known as Umtata.[2]

1397 Umtata
Discovery [1]
Discovered byC. Jackson
Discovery siteJohannesburg Obs.
Discovery date9 August 1936
Designations
(1397) Umtata
Named after
Mthatha [2]
(South-African town)
1936 PG · 1931 GK
1945 QF · 1945 RC
1948 EB1
main-belt · (middle) [3]
background [4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc81.14 yr (29,638 days)
Aphelion3.3646 AU
Perihelion1.9967 AU
2.6806 AU
Eccentricity0.2551
4.39 yr (1,603 days)
173.37°
0° 13m 28.56s / day
Inclination3.5109°
77.437°
206.53°
Physical characteristics
Dimensions20.35±0.30 km[5]
20.40 km (derived)[3]
20.798±0.292 km[6]
22.895±0.285 km[7]
30 h[8]
0.0794±0.0140[7]
0.084±0.046[6]
0.10 (assumed)[3]
0.112±0.004[5]
S/C [3]
B–V = 0.690 [1]
U–B = 0.210 [1]
11.47[1][5] · 11.57[3][7][8]

    Orbit and classification

    Umtata is a non-family asteroid of the main belt's background population.[4] It orbits the Sun in the central asteroid belt at a distance of 2.0–3.4 AU once every 4 years and 5 months (1,603 days). Its orbit has an eccentricity of 0.26 and an inclination of 4° with respect to the ecliptic.[1]

    The asteroid was first identified as 1931 GK at the Lowell Observatory in April 1931. The body's observation arc begins with its official discovery observation at Johannesburg.[9]

    Physical characteristics

    The asteroid's spectral type is unknown. The Lightcurve Data Base assumes an S- or C-type to be equally likely, using an average albedo of 0.10 (see below).[3][lower-alpha 1]

    Rotation period

    In May 1984, a rotational lightcurve of Umtata was obtained from photometric observations by American astronomer Richard Binzel. Analysis of the fragmentary lightcurve gave a rotation period of 30 hours with a brightness amplitude of 0.13 magnitude (U=1).[8] As of 2017, no secure period has been obtained.[3]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Umtata measures between 20.35 and 22.895 kilometers in diameter and its surface has an albedo between 0.0794 and 0.112.[5][6][7]

    The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 – a compromise value between the stony (0.20) and carbonaceous asteroid's, both abundant in the main belt's central region – and derives a diameter of 20.40 kilometers based on an absolute magnitude of 11.57.[3]

    Naming

    This minor planet was named after South-African town of Mthatha, formerly known as Umtata. It is the capital town of the OR Tambo District Municipality and the King Sabata Dalindyebo Local Municipality.[2] The official naming citation was published by the Minor Planet Center in April 1953 (M.P.C. 909).[10]

    Notes
    1. Asteroid Lightcurve Data Base (LCDB) – 2. Taxonomic Class, orbital class, and albedo. The LCDB generically assumes a S/C-type with an albedo of 0.10 for non-family main belt asteroids with a semi-major axis between 2.6 and 2.7.

    References
    1. "JPL Small-Body Database Browser: 1397 Umtata (1936 PG)" (2017-10-01 last obs.). Jet Propulsion Laboratory. Retrieved 17 October 2017.
    2. Schmadel, Lutz D. (2007). "(1397) Umtata". Dictionary of Minor Planet Names – (1397) Umtata. Springer Berlin Heidelberg. p. 113. doi:10.1007/978-3-540-29925-7_1398. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1397) Umtata". Asteroid Lightcurve Database (LCDB). Retrieved 17 October 2017.
    4. "Asteroid 1397 Umtata – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    5. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 17 October 2019. (online, AcuA catalog p. 153)
    6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 17 October 2017.
    7. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    8. Binzel, R. P. (October 1987). "A photoelectric survey of 130 asteroids". Icarus. 72 (1): 135–208. Bibcode:1987Icar...72..135B. doi:10.1016/0019-1035(87)90125-4. ISSN 0019-1035. Retrieved 17 October 2017.
    9. "1397 Umtata (1936 PG)". Minor Planet Center. Retrieved 17 October 2017.
    10. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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